In a detailed letter to the Chief Minister, ACT Greens environment spokesman Shane Rattenbury has also questioned science underpinning the cull, suggesting some data is more than 20 years out of date.

Mr Rattenbury has also raised concerns over ''serious safety risks'', citing claims in his letter that night-time shooting went ahead at one nature reserve, despite protesters being on-site. The letter also seeks to clarify reports that quad bikes were used to herd kangaroos during the cull, and suggests such ''herding'' does not comply with the ACT's Animal Welfare Act.

But a spokeswoman for Ms Gallagher said a number of claims outlined in the letter were inaccurate. In an emailed statement, the spokeswoman said ''all elements of the culling operations were quality tested'' against the ACT Code of Practice for the cull ''from the training of the marksman, the weapons and ammunition used''. She said an independent vet was engaged to audit the performance of the marksman, and the RSPCA was also ''invited to send their inspectors to overview the cull but elected not to do so''.

Australian Society for Kangaroos spokeswoman Fiona Corke said the ACT government had breached its own animal welfare laws by using quad bikes to herd kangaroos toward shooters. Herding may also be potentially in breach of a National Code of Conduct developed by federal and state governments for humane shooting of kangaroos and wallabies.

''We had reports that quad bikes were used during the cull at three reserves. In one case, a cyclone fence was battered and damaged as a result of panicked kangaroos being herded up against it,'' Ms Corke said.

Both the federal code and the ACT animal welfare laws state shooters must ensure each animal has died ''a sudden and humane death'' before moving on to shoot another. Both codes state animals ''must not be shot from a moving vehicle or other moving platform''.

The Chief Minister's office has confirmed quad bikes were used during the recent cull.

''Quad bikes were not used at any time to herd kangaroos during this cull. Culling operations do not involve the herding of animals. Quad bikes are used for riding around nature reserves to locate the kangaroo mobs,'' the office said in a statement.

''Once mobs are sighted they are approached no closer than 60 to 80 metres. Lights on the quads are off, night vision is used, speed is slow and the aim is to approach quietly so animals are not disturbed or startled to enable a clean shot.''

In recent weeks, the ACT government culled 1154 eastern grey kangaroos in nine nature reserves as part of a mangement plan to protect Canberra's grassland ecosystems.